In men and women sexual arousal culminates in orgasm, with female orgasm solely from sexual intercourse often regarded as a unique feature of human sexuality. However, orgasm from sexual intercourse occurs more reliably in men than in women likely reflecting the different types of physical stimulation men and women require for orgasm. In men, orgasms are under strong selective pressure as orgasms are coupled with ejaculation and thus contribute to male reproductive success. By contrast, women's orgasms in intercourse are highly variable and are under little selective pressure as they are not a reproductive necessity.. The proximal mechanisms producing variability in women's orgasms are little understood. In Marie Bonaparte proposed that a shorter distance between a woman's clitoris and her urethral meatus CUMD increased her likelihood of experiencing orgasm in intercourse.